The present invention relates to a physical quantity detection circuit, an electronic device, and a moving object.
A physical quantity detection device that detects an arbitrary physical quantity is known. For example, an angular velocity detection device that detects an angular velocity as the physical quantity is known, and an electronic device or a system that includes an angular velocity detection device, and performs a predetermined control process based on the angular velocity detected by the angular velocity detection device, is widely used. For example, a car (vehicle) travel control system may be configured to perform a travel control process that prevents a side skid based on the angular velocity detected by the angular velocity detection device.
Since such an electronic device or system may perform an erroneous control process when the angular velocity detection device has broken down, measures are taken (e.g., lighting an alarm lamp) when the angular velocity detection device has broken down, and various techniques have been proposed for implementing a breakdown diagnosis process on the angular velocity detection device. For example, JP-A-2010-286368 discloses a physical quantity detection device that changes the phase of a reference clock signal supplied to a synchronous detection circuit so that at least part of a leakage signal from a gyro sensor element is output.
According to JP-A-2010-286368, the synchronous detection circuit that extracts the leakage signal outputs a constant leakage signal using the reference clock signal of which the phase is fixed. Therefore, when the synchronous detection circuit has broken down, and outputs a constant value, it is difficult to detect that the synchronous detection circuit has broken down since it is difficult to determine whether or not the leakage signal output from the synchronous detection circuit differs from the leakage signal during normal operation.